1. Field of the Invention
The present invention relates to a medium conveying apparatus which can be applied to an image reader or printer, etc. In recent electronic document filing systems, image reading devices (referred to as scanners) have been widely used. It is desirable that such readers do not occupy a large space from the viewpoint of saving space. Note that the following discussion will be addressed to a scanner, but the invention can be equally applied to a printer or the like.
2. Description of the Related Art
In general, known scanners are grouped into two types, i.e., an ADF type (Automatic Document Feeder), and a flat bed type. The ADF is provided on the scanner. It is possible to set a plurality of documents to be read on the ADF at one time, and the documents can be automatically fed one by one. FIG. 29 shows a schematic view of an outer appearance of an ADF type scanner. In FIG. 29, 191 designates the hopper, 192 the reading portion, and 193 the stacker, respectively. 194 designates the conveyer passage. The documents stacked in the hopper 191 are successively fed to the reading portion 192 one by one and discharged therefrom onto the stacker 193. The scanner of the kind mentioned above exhibits a high reading efficiency since the documents are automatically fed.
FIG. 30 shows a flat bed type scanner. In the flat bed type scanner, there is a reading window (flat bed) 201 on the upper surface of the scanner. A reading portion 202 is provided in the scanner. In the scanner shown in FIG. 30, a document to be read is disposed on the reading window 201, and the reading portion 202 is moved in the directions indicated by arrows to scan and read the document. To read a plurality of documents, documents must be put on the reading window 201 one by one, and thus resulting in a lower reading efficiency. However, the flat bed type scanner is simpler in structure than the ADF type scanner, and accordingly is relatively inexpensive. This is the reason that the flat bed type scanners are often used by individuals who usually do not need to read a large number of documents using the scanner. However, the known scanners as mentioned above are not satisfactory in view of the use of space.
For instance, in case of the ADF type scanner, the stacker 193 extends out of the apparatus, thus leading to a large accommodation space. Moreover, the hopper 191 which receives documents disposed thereon partly projects upward. In addition, the hopper 191 is not strong enough to permit things to be put thereon. The fact that nothing can be put on the hopper also increases the amount of useless space.
In the case of the flat bed type scanner, the stacker or other elements do not project from the apparatus and accordingly the apparatus is relatively small. Nevertheless, since it is necessary for an operator to put the document on the reading window 201 formed on the upper surface of the scanner, the space above the apparatus cannot be effectively utilized, unlike the ADF type scanner.
These problems also occur in a printer or the like, in which sheets of paper to be printed are disposed on the hopper.
To solve the problems, the applicant of the present application has proposed an improved scanner in which an accommodation space can be effectively utilized (Japanese Patent Application No. 6-509826). FIGS. 31A and 31B show the proposed scanner.
The scanner illustrated includes a box type casing in and from which a hopper 211 having documents 215 to be read is inserted and withdrawn. Upon reading the document, the hopper is closed, so that the document is read by a reading unit provided in the apparatus. The document thus read is fed through a returning passage 213 and discharged into a stacker 214 which is provided for example in the lower portion of the apparatus. The reading unit is comprised of, for example, a close-contact sensor and is provided in a drawer type hopper in FIGS. 31A and 31B. The reading unit is not necessarily positioned in the hopper and can be instead provided in the apparatus body.
As can be seen from the foregoing, in the scanner illustrated in FIGS. 31A and 31B, there is no member necessary to read the document on the upper portion of the scanner, and accordingly, it is possible to put other devices such as a personal computer, on the scanner. Consequently, the substantial space for accommodating the scanner can be reduced.
In the scanner, the hopper is closed when the document is read and the hopper is opened for example when document is set in the hopper. However, if a paper jam occurs in the scanner, it is necessary to remove the jammed document from the apparatus. To this end, the apparatus is provided on the side wall thereof with an opening through which the jammed document can be removed by opening a cover at the opening.
A user may open the drawer type hopper to try to remove the jammed document. If the jammed document M is located in the hopper 211, as shown in FIG. 32A, or has been discharged from the hopper 211 as shown in FIG. 32B, there would be no serious problem even if the hopper 211 is opened.
However, as shown in FIG. 32C, if the hopper 211 is opened when the document M to be read is located partly in the hopper 211 and partly out of the hopper, the jammed document M which is held by rollers or the like within the apparatus can be creased or damaged.
The crease itself can be eliminated to some extent by flattening the document discharged from the apparatus, so that the document can be read. In the worst case, the document is destroyed, this resulting in the impossibility of re-reading the document.
Moreover, if the hopper is accidentally opened during the feeding of the document, not only can the document be damaged, but also, the feeding of the document can be interrupted. Accordingly, it is necessary to prevent the hopper from opening during the feeding of the document.
It is possible to provide a drawer type stacker in addition to the drawer type hopper shown in FIGS. 31A and 31B. In this alternative arrangement, the opening operation of the stacker could cause the document to be damaged.